Fig. 1. (Color online) (a) The process of planar structure photodiode fabrication through diffusion and the final device structure. (b) SEM diagram of the fabricated devices.

Fig. 2. (Color online) (a) SIMS test results. (b) The relationship between diffusion depth and diffusion temperature.

Fig. 3. (Color online) (a) The cross-section TEM image and (b) mapping energy spectrum of fabricated planar PN junction detector.

Fig. 4. (Color online) Simulation result of band structure based on SIMS data with a diffusion temperature of (a) 450 °C and (b) 550 °C.

Fig. 5. (Color online) The relationship between dark current density and bias at different temperatures for devices with diffusion temperatures of 450 and 550 °C.

Fig. 6. (Color online) The dark current mechanism of samples diffused at 450 and 550 °C.

Fig. 7. Performance curve and wavelength of the photodiode with a diffusion temperature of (a) 550 °C and (b) 450 °C.

Fig. 8. Infrared radiation imaging of (a) electric soldering iron and (b) lighter flame.